Grid-leak cell circuit



C. F. JENKINS I- GRID LEAK can. cnicurr Re. 17,766

Original Filed Oct. 22, 1924 Reissued Aug. 12, 1930 UNITED STATESCHARLES FRANCIS JENKINS, JENKINS LABORATORIES, 'IION on THE DISTRICT orCOLUMBIA PATENT OFFICE GBID-LEAK CELL CIRCUIT Original No. 1,667,384,dated April 24, 1928, Serial No. 745,211, filed October 22, 1924.Application for reissue filed January 30, 1930. Serial No. 424,700.

This invention relates to radio circuits in which a light-sensitive celltakes the place of a grid leak in an oscillation generator circuit, andhas for its principal object such an adjustment of the component partsas will stop and start oscillation in accord with the light and darkcondition of the cell.

With this and other objects, the invention consists of the employmentand arrangement of the several elements described in the followingspecifications, illustrated in the drawing, and particularly pointed outin the claims.

In the drawings A is a light sensitive cell;

B a three-element tube; and C as oscillationgenerating coupling coil.

With the several parts adjusted for oscillation of the circuit whenlight falls on the cell, the oscillation will instantly ceasewhen thelight is cut off, because of the increase in the resistance of the cell.The output of the oscillating circuit is, therefore, intermittent, theintermittence depending upon the order of the light falling on the cell.

No means for intermittently illuminating the cell is shown as this is nopart of the invention and not essential to an understanding of itsoperation.

What is claimed is:

1. The combination with an electron valve, of a circuit including inputand return conductors connected respectively with the grid and filamentelectrodes of the valve, a variable stopping condenser in series withsaid input conductor, and a resistance leak in said input conductorshunted about the condenser and comprising a light sensitive cell.

- 2. The method of operating an electron discharge device to produceinterrupted radio frequency wave trains which includes the step ofintermittently exposing a light sensitive grid leak to light, to controlcessation of oscillations in said device.

3. The method of starting and stopping os cillations from an electrondischarge oscillator having a condenser in series with the grid of saidoscillator, which comprises shunting said condenser with a lightresponsive device 50 and adjusting the values of said condenser so thatwhen light falls on said device oscillations are started and when lightis out OK said device ceases oscillating.

4. In combination with an electron discharge device of circuitconnections for causing said device to generate oscillations andoscillation control means comprising a condenser connected between oneend of an input coil and the grid of said device, and a light sensitivedevice shunted about said condenser,

5. The combination according to claim 4 in which said condenser isvariable.

v6. In combination, an electron discharge device having an input circuitand an output circuit, means for feeding back energy from said outputcircuit to said input circuit, and a light-sensitive cell grid leak forsaid oscillator in series with the input circuit to control the startingand stopping of oscillations in accordance with signals.

7 In combination, an electron discharge oscillator of the feed backtype, and a lightsensitive cell grid leak connected in series with theinput circuit of said oscillator.

In testimony whereof I have hereunto set my hand on this 25th day ofMarch, 1930.

CHARLES FRANCIS JENKINS.

